/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.messages.checkpoint;

import org.apache.flink.api.common.JobID;
import org.apache.flink.runtime.executiongraph.ExecutionAttemptID;

/**
 * The base class of all checkpoint messages.
 */
public abstract class AbstractCheckpointMessage implements java.io.Serializable {

	private static final long serialVersionUID = 186780414819428178L;
	
	/** The job to which this message belongs */
	private final JobID job;
	
	/** The task execution that is source/target of the checkpoint message */  
	private final ExecutionAttemptID taskExecutionId;
	
	/** The ID of the checkpoint that this message coordinates */
	private final long checkpointId;

	
	protected AbstractCheckpointMessage(JobID job, ExecutionAttemptID taskExecutionId, long checkpointId) {
		if (job == null || taskExecutionId == null) {
			throw new NullPointerException();
		}
		
		this.job = job;
		this.taskExecutionId = taskExecutionId;
		this.checkpointId = checkpointId;
	}

	// --------------------------------------------------------------------------------------------
	
	public JobID getJob() {
		return job;
	}

	public ExecutionAttemptID getTaskExecutionId() {
		return taskExecutionId;
	}

	public long getCheckpointId() {
		return checkpointId;
	}

	// --------------------------------------------------------------------------------------------

	@Override
	public int hashCode() {
		return job.hashCode() + taskExecutionId.hashCode() + (int) (checkpointId ^ (checkpointId >>> 32));
	}

	@Override
	public boolean equals(Object o) {
		if (this == o) {
			return true;
		}
		else if (o instanceof AbstractCheckpointMessage) {
			AbstractCheckpointMessage that = (AbstractCheckpointMessage) o;
			return this.job.equals(that.job) && this.taskExecutionId.equals(that.taskExecutionId) &&
					this.checkpointId == that.checkpointId;
		}
		else {
			return false;
		}
	}

	@Override
	public String toString() {
		return "(" + checkpointId + ':' + job + '/' + taskExecutionId + ')';
	}
}
